Music is a universal phenomenon which involves a unique complex of perceptual and cognitive functions. This proposal is an attempt to initiate the establishment of neurophysiological basis for the understanding of musical cognition in normal aging and in persons with senile dementia of the Alzheimer's type (SDAT). Our goal is to fill two serious gaps in present understanding. First, studies of musical cognition and performance in older persons have been largely neglected. Second, while music is anecdotally well known to be a great benefit to persons suffering from SDAT, hardly any scientific experimentation has been done to characterize and understand this phenomenon. The objectives of the project are: 1) to demonstrate quantifiable neurophysiological measures which consistently and perhaps uniquely correspond to musical perception and cognition; 2) to discover differences in musical task strategies and performance levels as a function of age, presence of SDAT, and degree of musical training; 3) to correlate these differences with differences in neurophysical activity; 4) to use current understanding of musical cognition to enhance understanding of event-related potentials. To accomplish these goals, normal adult subjects, both young and old, and subjects with SDAT will participate in an extensive five-year series of increasingly complex controlled psychophysical and cognitive experiments during which neurophysiological measurements will be taken. Subjects will be classified according to their degree of musical training. The neural measurements will focus on endogenous event-related potentials, especially the P300 and N4 potentials which correlate with the updating of working memory and the detection of semantic incongruity, respectively. The experiments will involve discrimination of intervals, timbres, and rhythmic figures, and cognition of meter and of melodic and harmonic closure and incongruity. We expect that measurements of neural activity will detect differences not obtainable from non-neurophysiological measures alone. Thus, different groups with equal performance measures may exhibit differences in event-related potentials symptomatic of qualitative and quantitative differences in cognitive processing. Our studies will yield fundamental knowledge about the largely unstudied musical dimension of cognition and creative ability in older persons.